Various techniques of forming a coat on the surface of metal are known for the purpose of preventing corrosion of metal or preventing stains.
Patent Literature 1 discloses perfluoropolyether benzotriazole compounds and compositions containing perfluoropolyether benzotriazole compounds. It also discloses that the perfluoropolyether benzotriazole compounds can be attached to a metal substrate to provide at least one of the following characteristics: anti-soiling, anti-staining, ease of cleaning, repellency, hydrophobicity, or oleophobicity.
Patent Literature 2 discloses that a copolymer synthesized from a structural unit of such a monomer as 1-vinyl imidazole can provide corrosion-control coats.
Electronic devices include circuit boards provided with conductive lines formed of metal coats. However, the metal coats are brought into contact with water or corrosive gas and are eroded, so that the conductivity thereof degrades. Further, optical devices such as light-emitting diodes suffer discoloration due to corrosion of metal coats, so that the brightness thereof degrades. In order to solve these problems, various methods of preventing corrosion of metal coats by forming a coat on metal films are known.
For example, Patent Literature 3 discloses a coating composition for sealing conductive parts such as conductive lines, electric contacts, and electric wires of traffic signals or lighting apparatus to provide characteristics such as water resistance, insulation, durability, and resistance to decomposition due to ultraviolet rays, essentially consisting of a fluoropolymer which is soluble in a solvent and has a molecular weight of 10,000 or higher, and a solvent which dissolves the fluoropolymer.